1. Field of the Invention
The present invention relates to a manifold facsimile apparatus capable of selectively communicating with a G3 (Group 3) facsimile terminal as prescribed by CCITT (Consultation Committee of International Telegraph and Telephone), i.e., an analog facsimile terminal using a public telephone network, and a G4 (Group 4) digital facsimile apparatus standard functions of which will be prescribed by CCITT in the near future.
2. Discussion of Background
A facsimile apparatus designed for visual communication has been remarkably scaled up in function to even acieve a capability for transmitting a standard document of A4 format within less than one minute. CCITT has recommended basic functions of facsimile transceivers and standardized the specifications, data link controls and others associated with the same. To date, Recommendations T.2, T.3, T.4 and T.30 are available for G1 (Group 1) to G3 (Group 3) transceivers all of which are analog transceivers using analog communication networks, e.g. a public telephone network.
Further, CCITT is now preparing a recommendation which prescribes the specification, data link control and other standard functions of a G4 facsimile apparatus, which is an advanced version of a G3 apparatus. A G4 facsimile apparatus is expected to feature high resolution and use a system which is higher in compression efficiency than the others. Such an apparatus, therefore, allows visual communication to be accomplished with quality superior to that of a G3 apparatus. Basically, a G4 apparatus is a digital facsimile apparatus which uses a digital network for communication and, for this reason, it has a data link control function capable of sufficiently utilizing the advanced communication function of a digital network. Digital switched networks, packet networks and other digital communication networks have recently been constructed and are deemed to become open to the public soon. Such a trend is accelerating the development of a digital facsimile transceiver which uses a digital communication network.
In the above situation, there arises a need for mutual communication between a traditional G3 analog facsimile apparatus and a G4 digital facsimile apparatus which will become predominant in the future. However, since an analog facsimile apparatus and a digital facsimile apparatus are incapable of communicating with each other due to the different kinds of networks they use, digital apparatuses which will be installed cannot be connected to a facsimile communication path which is implemented with existing analog apparatuses.